Anodizing method



W. W. HERRICK ANODIZING METHOD Feb. 27, A1945.

Filed June 19, 1943 i .L 331, 33 37 y? 9' 35 m32 3/ f/a.

29a ..36 #6h/7l.' .30 34 gq I9 l Z6* ZZ ZI 2/ l L" 261, 23 20 lg l H INVENTOR y M( W//son Herr/'ck BY Qa'n- ,Cum Hav-Y a ATTORNEY l Patented Feb. 27, 1945 ANODIZING METHOD William Wilson Herrick, Stamford, Conn., as-

signor of twenty-five per cent to Percival W. Whittiesey, Stamford, and twenty-five per cent to Benton Blair, Darien, Conn.

Application June 19, 1943, Serial No. 431,432

, 3 Claims.

This invention relates to a method of anodizing and yto apparatus for use in connection therewith.

One of the objects of this invention is to provide new and improved apparatus for anodizing. Another object is to provide apparatus of the above character which will be simple, practical, and thoroughly durable. Another object is to provide apparatus of the above character, the operation of which will result in substantial saving of labor. Another object is to provide apparatus of the vabove character which will be sturdy and will be able to withstand hard usage. A further object isto provide apparatus of the above character, in which a maximum of articles may be anodized in a minimum of time. Still another object is to provide a new and improved method of anodizing. A still further object is to provide an eicient and practical anodizing method. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts, and in the several steps and relation and order of each of the same to one or more of the others, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing in which is shown one of the various possible embodiments of this invention,

. mounted on a bracket, generally indicated at I2,

Figure l is a side elevation of the anodizing apparatus, certain parts thereof being in section; and,

Figure 2 is a horizontal section taken on the line 2-2 of Figure 1.

Similar reference characters refer to similarv parts throughout the several views ofthe-drawing.

As conducive to a clearer understanding of certain features of this invention, it might here be pointed out that considerable dimculty has been experienced with present methods of anodization and apparatus used in connection therewith. One of the principal methods now in use is to connect Aeach article being anodized to the source of current by a conductor. This practice is inefficient because of the labor and time required to properly connect articles to conductors. Other methods of forming the necessary electrical connection with the articles to' be anodized, such as packing the articles under compression in an anodizing chamber, have not solved this problem because proper electrical condicated at I 0. This container is preferably made Vof aluminum and holds the articles being anodized during anodization. This container is rotated through means to be described hereinafter by a motor, generally indicated at I I, and is connected to the positive side of a source of current. The articles within the container I0 are held by centrifugal force against the side wall of the container II! and against each other, thus assuring a good electrical connection between each article and the positive source of current.

Specifically, container Iii and motor li are which is vertically movable on a support, generally indicated at I3. Bracket I2 is mounted on a column I4 for vertical movement with respect thereto and may be held in a set position with respect thereto by a set screw I5. Bracket I2 includes left and righthand sections I6 and Il which are insulated from each other. Preferably, these sections have flanges Ilia and Ila formed thereon which are separated by electrical insulation material I8. Bolts I9 extend through anges Ilia and I'la and insulation material I8 to hold sections I6 and Il in assembled relationship. Bolts I3 are insulated from anges I6a and I'Ia by insulating sleeves 20 and by sheets of insulating material 2l. Thus, sections I6 and I1 when in assembled relationship are electrically insulated from each other.

Section I6 has a pair of arms 22 and 23 having bearings 24 and 25 mounted in the ends thereof. positioned with respect to the electrolyte tank 21, is mounted for'rotational movement in bearings 24 and 25. This shaft has a pulley, generally indicatedat 29, connected to its upper end in any suitablemanner, such as'by brazing. This pulley is driven by motor I I through motor pulley IIa and belt 3|. A thrust bearing 30 is positioned between the hub 29a of pulley 29 and the upper surface of arm 22 to permit free rotation of container l0 by motor II.

Electrical contact is established between positive conductor 32 and shaft 26-through a metal A metal shaft 26, which is vertically contactor, generally indicated at 23. This contactor includes an arm 38a pivotally connected by pin 34 to a portion I8b of bracket I2. Another arm 33h of -contactor 38 extends inwardly over pulley 29 and has a carbon brush contact member 35 extending downwardly from its left-hand end, as viewed in Figure 1. A spring 88 connected to 'the under side of arm 33 and to bracket I2 resiliently urges the brush contact member into contact with the upper end of shaft 28. Thus the contacter establishes an electrical connection between shaft 28 and conductor 32.

Anodizing container I includes a cylindrically shaped side wall Ilia (Figure 2) and a bottom lilb (Figures 1 and 2). A metal shaft 42 extends through the center of the anodizing container mize the out-of-balance strain upon bearings 24 and 25 during operation ofthe apparatus.

The bottom IIIb, side wall Ilia, and partitions 43 are perforated. The perforations in the side wail Illia permit the electrolyte in the container to be thrown outwardly during rotation of container I0 and the perforations in the bottom of the container and its open top permit the electrolyte to enter the container. The perforations in the partitions permit the electrolyte to circulate around shaft (i2 within the container, and the number, position, and size of these perforations, in addition to the number, position, and size of the perforations in the side wall of the container, may be used to control the degree of circulation through the container. Furthermore, it should be noted that the number and size of the perforations are van'ed to suit the size of the articles being anodized and that the number and size of the perforations shown in the `drawing are diagrammatic. Thus, excellent circulation of the electrolyte through the anodizing container during anodization is assured. v

To supplement circulation of the electrolyte through the container described hereinabove, a pair of fins 40 and 4i may be mounted on the Abottom ib and extend therebelow. When the anodizing container is rotated, these fins force the electrolyte up through the perforations in the bottom of the anodizing container. Thus, the perforations in the side wall a, the open top of the container, the perforations in the bottoii lub, and the fins 40.and 4I cause circulation of the electrolyte through Ithe container in the direction of the arrows in Figure l during anodization.

The upper end of shaft 42 has a. flange 42a These easily disconnected from shaft 28. Furthermore. the connection of shafts 42 and 28 completes the electrical connection between container I0 and conductor 82, the current during operation of the apparatus passing through shaft 28, shaft 42, and radial partitions 43 into container side wall Illa.

The tank 21 holding electrolyte 28 preferably consists of a shell 21a made of an insulating material having a steel lining 21h. Lining 2lb is connected to electrical conductor 41 in any suitable manner such as by screw 48. To aid in moving bracket I2 and its associated parts upwardly and downwardly with respect to column I4 and thus move the container |10 out of the electrolyte in tank 21, a counterweight (not shown) is provided. This counterweight is connected by a cable 88 (Figure 1) to bracket I2, and when it is desired to remove the container I0 from tank 21, set screw il is loosened and bracket I2 and its associated part may be easily moved upwardly on column I4.

In operation, tank 21 is filled with an electrolyte suitable for anodizlng, such as chromic acid. Next container i0 is loaded with the articles to be anodized, connected to shaft 28 by nuts 48, and then the bracket I2 is lowered so that the top of container IIJ is positioned a substantial distance below the level of the electrolyte in tank 21. This insures contact of the electrolyte with vall of the articles being anodized when container I0 is being rotated during the anodizing process. Next the switch for motor II is thrown and container I0 is rotated at a speed of approximately 600 R. P. M. It should be noted here that the rate of rotation of container Iii may be varied and that the rate depends-on both the size of the articles being anodized and the diameter of the container. The rate ofl rotation should be sufficient to cause centrifugal force to throw the larticles outwardly from shaft t2 against wall Illa with sufficient force to establish good electrical contact between the articles and the Wall Illa of the container and between the articles themselves.

After the container Iii has reached this speed,

i the switch controlling the passing of current thereon and a frusto-cone 42h extending thereabove. The lower end of shaft 28 has a flange 28a formed thereon and a hole 28h complementary to the shape of frusto-cone 42b extending upwardly therein. When frusto-cone 42b is seated in hole 2Gb, the axes of shafts 28 and 42 are aligned and flanges 28a and 42a abut against each other. Bolts 48, which extend through flanges 26a4and 42a hold shafts 28 and 42 in assembled relationship. These bolts are provided with knurled nuts 48a, thus permitting shaft 42 and accordingly the anodizing container to be ,mainder of the articles in the container.

through the electrolyte is thrown. By waiting until good electrical contact is established between the container and the articles before throwing the switch, damage to the articles through arcing at partially established contact points is prevented. When the switch is thrown, current from conductor82 passes through shaft 28 and shaft 42 into the partitions 43 and wall Ina ofthe anodizing container i0, the circuit to conductor 41 being completed through the electrolyte and the steel lining 2lb of tank 21. From -the wall and partitions. the current passes into the articles in contact with the side wall and partitions of the container and thence into the re- Thus. centrifugal force insures a good contact between the positive source of current and all of the articles being anodized in the container i0. Furthermore, during rotation of container I0, excellent circulation of the electrolyte through the container is maintained as described hereinabove.

The container is rotated for a sufcient time to form an anodic film on the articles being anodized. The centrifugal force normally holds the articles locked or immobilized in set positionsl throughout the period during which the container is rotated. This prevents damage to the articles and also prevents damage to the anodic film being formed on them. However, if an article should shift its position during anodization, the pressure of the centrifugal force is suiiicient to break through the electrical resistance of the anodic illm already formed on the article and form a new electrical contact between the container and the article so that anodization of the article is completed.

' After the anodic lm has been formed, the current passing through the electrolyte and the current to the motor are shut 01T in succession. Then container IU is raised, removed from bracket I2', and the articles given a cold water rinse followed by a hot water seal. After this, the work is air-dried and dumped from the container I0. The anodizing container I0 is then stripped of the anodic iilm formed thereon during anodization to assure a good contact between the new load to be placed therein and the container. The anodic lm may be stripped by placing the container in a caustic bath.

It will thus be seen that practical and eiiicient apparatus for anodizing a plurality of articles at one time has been disclosed. The use of this apparatus results in substantial saving of labor and time and also results in the formation of a good anodic film on the articles being anodized. Furthermore, a practical and eiiicient method of anodization has been disclosed.

As many possible embodiments may be made of the mechanical features of the above invention and as the art herein described might be varied in. various parts, all without departing from the scope of the invention, it is to be understood that vall matter hereinabove set forth, or shown in the accompanying drawing is to be interpreted as il lustrative and not in a limiting sense.

I claim: v

1. In a. process for anodizing a multiplicity of aluminumarticles, the steps of loading a cylindrical metal container with the articles to be anodized, connecting the container to the anode of an anodic treatment bath, and rotating said container in the anodic bath with sufcient speed the articles to be anodized, connecting the container to the anode of an anodic treatment bath, rotating said container in said anodic bath with suicient speed to utilize centrifugal force solely to establish ilrm electrical contacts with the side wall of said container and with each other and to hold said articles in set positions during the v period of anodic treatment, and then energizing the circuit throughA said anodic bath.

3. In a process for anodizing a multiplicity of aluminum articles, the steps of loading a perforated cylindrical metal container with the articles to be anodized, connecting the perforated metal container to the anode of an anodic treat-A ment bath, rotating said container in the anodic bath with suiiicient speed to utilize centrifugal force to cause the articles to establish iirm elec-`.

trical contacts with the side wall of said container and with each other and to hold said articles immobilized in set positions during the period of anodic treatment, and circulating the anodic bath through the container and between said articles during anodization.

W. WILSON HERRICK. 

